From patchwork Wed Oct 11 12:46:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicola Vetrini X-Patchwork-Id: 13417357 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7E096CD6E67 for ; Wed, 11 Oct 2023 12:47:14 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.615479.956728 (Exim 4.92) (envelope-from ) id 1qqYc5-00064k-OG; Wed, 11 Oct 2023 12:46:57 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 615479.956728; Wed, 11 Oct 2023 12:46:57 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qqYc5-00064b-LB; Wed, 11 Oct 2023 12:46:57 +0000 Received: by outflank-mailman (input) for mailman id 615479; Wed, 11 Oct 2023 12:46:55 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qqYc3-0005p0-JH for xen-devel@lists.xenproject.org; Wed, 11 Oct 2023 12:46:55 +0000 Received: from support.bugseng.com (mail.bugseng.com [162.55.131.47]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 41602134-6834-11ee-9b0d-b553b5be7939; Wed, 11 Oct 2023 14:46:54 +0200 (CEST) Received: from nico.bugseng.com (unknown [147.123.100.131]) by support.bugseng.com (Postfix) with ESMTPSA id DCCF84EE0748; Wed, 11 Oct 2023 14:46:51 +0200 (CEST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 41602134-6834-11ee-9b0d-b553b5be7939 From: Nicola Vetrini To: xen-devel@lists.xenproject.org Cc: sstabellini@kernel.org, michal.orzel@amd.com, xenia.ragiadakou@amd.com, ayan.kumar.halder@amd.com, consulting@bugseng.com, jbeulich@suse.com, andrew.cooper3@citrix.com, roger.pau@citrix.com, Nicola Vetrini , Simone Ballarin , Doug Goldstein , George Dunlap , Julien Grall , Wei Liu Subject: [XEN PATCH][for-4.19 v2 1/1] xen: introduce a deviation for Rule 11.9 Date: Wed, 11 Oct 2023 14:46:46 +0200 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 The constant 0 is used instead of NULL in '__ACCESS_ONCE' as a compile-time check to detect non-scalar types; its usage for this purpose is deviated. Furthermore, the 'access_field' and 'typeof_field' macros are introduced as a general way to deal with accesses to structs without declaring a struct variable. No functional change intended. Signed-off-by: Nicola Vetrini Reviewed-by: Stefano Stabellini --- Changes in v2: - added entry in deviations.rst --- automation/eclair_analysis/ECLAIR/deviations.ecl | 9 +++++++++ docs/misra/deviations.rst | 5 +++++ xen/include/xen/compiler.h | 5 ++++- xen/include/xen/kernel.h | 2 +- 4 files changed, 19 insertions(+), 2 deletions(-) diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl b/automation/eclair_analysis/ECLAIR/deviations.ecl index fa56e5c00a27..28d9c37bedb2 100644 --- a/automation/eclair_analysis/ECLAIR/deviations.ecl +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl @@ -246,6 +246,15 @@ constant expressions are required.\"" "any()"} -doc_end +# +# Series 11 +# + +-doc_begin="This construct is used to check if the type is scalar, and for this purpose the use of 0 as a null pointer constant is deliberate." +-config=MC3R1.R11.9,reports+={deliberate, "any_area(any_loc(any_exp(macro(^__ACCESS_ONCE$))))" +} +-doc_end + # # Series 13 # diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst index ee7aed0609d2..1b00e4e3e9b7 100644 --- a/docs/misra/deviations.rst +++ b/docs/misra/deviations.rst @@ -199,6 +199,11 @@ Deviations related to MISRA C:2012 Rules: See automation/eclair_analysis/deviations.ecl for the full explanation. - Tagged as `safe` for ECLAIR. + * - R11.9 + - __ACCESS_ONCE uses a 0 as a null pointer constant to check if a type is + scalar, therefore its usage for this purpose is allowed. + - Tagged as `deliberate` for ECLAIR. + * - R13.5 - All developers and reviewers can be safely assumed to be well aware of the short-circuit evaluation strategy for logical operators. diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h index dd99e573083f..15be9a750b23 100644 --- a/xen/include/xen/compiler.h +++ b/xen/include/xen/compiler.h @@ -109,13 +109,16 @@ #define offsetof(a,b) __builtin_offsetof(a,b) +/* Access the field of structure type, without defining a local variable */ +#define access_field(type, member) (((type *)NULL)->member) +#define typeof_field(type, member) typeof(access_field(type, member)) /** * sizeof_field(TYPE, MEMBER) * * @TYPE: The structure containing the field of interest * @MEMBER: The field to return the size of */ -#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) +#define sizeof_field(TYPE, MEMBER) sizeof(access_field(TYPE, MEMBER)) #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 201112L #define alignof __alignof__ diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h index 46b3c9c02625..2c5ed7736c99 100644 --- a/xen/include/xen/kernel.h +++ b/xen/include/xen/kernel.h @@ -51,7 +51,7 @@ * */ #define container_of(ptr, type, member) ({ \ - typeof( ((type *)0)->member ) *__mptr = (ptr); \ + typeof_field(type, member) *__mptr = (ptr); \ (type *)( (char *)__mptr - offsetof(type,member) );}) /*